Heat exchanger



M. VAN ES Nov. 11, 1969 HEAT EXCHANGER Filed Dec. 12, 19s? United States Patent 3,477,501 HEAT EXCHANGER Machiel van Es, 'Amsterdam, Netherlands, assignor to Gebr. Stork & Cos Apparatenfabriek N.V., Amsterdam, Netherlands Filed Dec. 12, 1967, Ser. No. 689,842 Int. Cl. F28f 27/02; F28d 7/10 US. Cl. 165-103 2 Claims ABSTRACT OF THE DISCLOSURE A heat exchanger comprising a tubular element divided into two spaces by a wall, one of the spaces being con nected to a supply and to a discharge conduit for a condensable heat-carrier the other space being traversed by the product to be heated, said discharge conduit being connected via a bypass to at least one other location of said tube.

My invention relates to a heat exchanger which is applied as a pasteuriser or sterilizer for a combination of a number of machines, like e.g. filling or packing machines. The product to be treated should be heated, which treatment is eifected in the heat exchanger.

It often occurs that one or more of the machines of the group cooperating with the heat exchanger are turned ofi. The capacity of the heat exchanger should then be reduced accordingly. In the known device this is no problem because the heat exchanger consists of as many portions as there are machines combined with one another. In that case the supply of the heating fluid to one or more portions of the heat exchanger is simply cut off so that the product to be treated flows simply through these portions without any heat exchange being ettected.

My inventive conception starts from a modified type of a heat exchanger, know per se, consisting of a tube with at least two parallel spaces separated by a wall, wherein one of the spaces is connected to a supply and to a discharge conduit for a condensable heat-carrier, such as steam, while the product to be heated flows through the other space. In such a heat exchanger it is not possible to turn 01f one or more portions.

It is an object of my invention to render it also possible in this type of heat exchanger to ettectuate a partial cut off. This object is attained according to my invention in that the discharge conduit of the heat-carrier is connected via a bypass to various locations of the tube, said locations being distributed over the length of said tube, and in that at least the most downstream situated connections of said'bypass are provided with a valve, whereby those portions of the space through which the heating fluid flows, situated between these connections, are lying below said connections. Due to these features a portion of the space through which the heat-carrier flows can be turned off, whereupon this portion soon fills with condensate, so that the heat-carrier can no longer enter that portion.

My invention relates especially to a heat exchanger whereby in a way known per se the tube consists of two concentrical pipes, wound into a helix with a vertical centre line. A further object of my invention is to be able to reduce the capacity of the heat-exchanger step wise so that a smaller or greater part of the device can be rendered inoperative.

The foregoing and other objects and advantages of my invention will appear in the description to follow. In the description reference is made to the accompanying drawing, which form a part hereof, and in which there is shown by way of illustration and not of limitation a specific form in which my invention may be embodied.

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FIG. 1 is a first embodiment of a heat. exchanger curved in three dimensions.

FIG. 2 shows a section of a small part of an embodiment wherein the heat exchanger is curved in two dimensions.

The heat exchanger consists of a tube with at least two parallel extending spaces separated by a wall, e.g. a double walled tube which is wound so as to form an upright helix represented in outline in FIG. 1. Such a spiral may for instance be manufactured according to the Netherlands Patent -176. The product to be heated e.g. milk, is supplied to the lower end 1 of the inner pipe 2. This is indicated by a plain line arrow in FIG. 1. The heat-carrier e.g. steam, is led in the usual way in an opposite direction through the heat exchanger, that is to say the inlet is connected to the upper end 3 of the outer pipe 4. The discharge 5 of the heat-carrier is connected to the pipe 4 at the lower end 6. Via a bypass 7 the discharge 5 is connected at the locations 8 and 9 to the space through which flows the heat-carrier. Valves 10 and 111 are provided at the location of the connection 6 and 9 respectively. A condenser 12 is disposed in the discharge 5.

The situation with respect to the pipe 4 is such that its portions 4 and 4 lying between the connections 6, 9 and 8 are below the connections 8 and 9 respectively. Normally, when the complete heat exchanger is used, the valves 10 and 11 are open, so that the heat-carrier flows substantially, via the connection 6, to the discharge 5. When now the capacity of the heat exchanger should be reduced, for instance to /3, the valve 1.0 is closed so that the heat-carrier flows to the discharge 5 via the connection 9 and the bypass 7. The condensate of the heat-carrier will gradually accumulate in the portion of the pipe 4 between the valve 10 and the connection 9. In this manner no heat transfer worth mentioning can further occur in the portion 4 of the heat exchanger.

A similar phenomenon takes place when the capacity of the heat exchanger should be reduced further and the valves 10 and 11 are closed. Since for a real reduction of capacity of the heat exchanger it is essential that the turned off portions 4' and eventually 4 of the pipe 4 fill with condensate, the position of the portions of the double walled tube in the area between the connections 6, 9 and 8 should exactly be in the manner as described hereinbefore, so that the aforementioned parts can fill with condensate. Consequently it is not essential for the invention that the heat exchanger consists of a helix with a vertical centre line, provided the arrangement is such that the condensate can accumulate in the turned otf portion of the space for the heat-carrier.

FIG. 2 shows another embodiment of the heat exchanger. This one consists of two parallel spaces 13 and. 14 separated by a wall 15. This box-shaped tube has a zig zag shape extending in a single plane and therefore not in three dimensions like the spiral according to FIG. 1. The embodiment according to FIG. 2 can be applied in a practically horizontal position, the connection of the bypass (not shown) in that case being provided at the upper side of the box-shaped tube, so that the space 13 through which flows the heat-carrier is situated below the connections.

It is obvious that the number of connections of the discharge and of the bypass to the space through which the heat-carrier flows is not limited to the three locations shown in FIG. 1. The number of connections is determined in dependence on the requirements to be met by the heat exchanger and on the portions which now and then should be turned off. In the described embodiment the product to be treated flows in counter-flow with respect to the heating fluid. This is not essential either for the invention since the basic idea thereof can also be applied in case of a parallel fiow direction.

In the embodiment according to FIG. 1 it is possible to provide an extra valve in the proximity of the connection 8 in order to prevent any possible loss of the heat-carrier via the bypass 7 when the heat exchanger is fully used. It has been found in practice that this loss is negligible so that no valve is requisite with the connection 8.

The invention can also be applied to a plate heat exchanger, provided the arrangement is such that the turned off portions can fill with condensate.

While a preferred embodiment of my invention has been shown and described, it is to be understood that changes and variations may be made without departing from the spirit and scope of my invention as defined in the appended claims.

What I claim is:

1. A heat exchanger for the thermal treatment of a heat sensitive liquid and comprising two concentric pipes wound into a helix having a vertical center line, the lower end of the inner pipe being connected to a supply of liquid to be heated and the heated liquid being discharged from the upper end thereof, the upper end of the outer pipe being connected to a source of steam, a steam discharge conduit connected to the lower end of said outer pipe, a plurality of bypass connections between 4:, a corresponding plurality of points locateddown stream of said steam source along the length of said outer and said steam discharge conduit, a control valve in at least each of the lowermost bypass connections, the portions of the outer pipe between the connections to the steam discharge line being below the bypass connections.

2. A heat exchanger as claimed in claim 1 with vthe re being three connections between said outer pipe and said steam discharged line with control valves beingin the two lower connections. 1 1

References Cited 3 Lavigne 165- 163 ROBERT A. OLEARY, Primary Examiner C. SUKALO, Assistant Examiner U.S. Cl. X.R. 165154 

